Among various biocides known, peroxycarboxylic acids are increasingly used as antimicrobials and bleaching agents in many applications, owing to their high efficacy against a broad spectrum of microorganisms, color safe property, low residues and nontoxic nature of their decomposition products. Peracetic acid is the most commonly used peroxycarboxylic acid and has been shown to be a good biocide, but only at relatively high concentrations (generally greater than 80 part per million). Similarly, peroxyfatty acids have also been shown to be biocidal, but only at high concentrations (greater than 200 ppm), such as in the composition disclosed in European Patent Application No. 233,731. In contrast, peroxyformic acid has an advantageous degree and range of microcidal properties compared to other peroxycarboxylic acids, such as peracetic and perproprionic acids, as disclosed by V. Merka et al in J. Hyg. Epidem. Microbiol. Immunol, 1965 (IX) 220, as well as in European Patent Application No. 863,098,96.
Peroxycarboxylic acid compositions are generally made through an acid catalyzed equilibrium reaction. Most often, the peroxycarboxylic acids are generated in a chemical plant, and then shipped to customers for on-site use. Due to the limited storage stability of peroxycarboxylic acids, the peroxycarboxylic acids must be packed in special containers and shipped under strict Department of Transportation (DOT) guidelines. Further, excess amounts of reagents (e.g., acids, oxidizing agents, and stabilizers) are present in the compositions during shipping to prevent decomposition. For peroxyformic acid, however, the inherent instability of the substance relative to the higher alkyl peracid, and the explosive nature of the substance at the concentrate make it an even more significant challenge to be manufactured, stored and transported before dilution prior to use, in the similar way like higher alkyl peracid. Thus, there are needs for the on-site generation of peroxycarboxylic acids, especially peroxyformic acid.
It is known in the art that peroxycarboxylic acids could be alternatively generated in situ through the perhydrolysis of the higher alkyl carboxylic acid esters of polyhydric alcohol, as disclosed in the Patent Application No. WO2012/090124 and U.S. Pat. No. 7,919,122. The perhydrolysis reaction, however, has to be carried out under strong alkaline conditions, for example at pH greater than 12, or at least keeping the pH of the solution between 10 to 12 during the perhydrolysis reaction. As a result, the solution has to be acidified after the perhydrolysis reaction in order to bring the generated peroxycarboxylic acid in the form to be efficient as biocide. One approach to increase the perhydrolysis reactivity of the esters is using perhydrolysis enzyme, such as disclosed in U.S. Pat. No. 8,865,436. With the help of the enzyme, the reaction could be carried out in close to neutral pH conditions, and thus avoid the acid neutralization process. However, the enzyme itself is expensive, and including the enzyme in the system will also increase the delivery complexity.
There is a need to seek alternative ways to generate peroxycarboxylic acids, namely peroxyformic acids. The present disclosure addresses this and the related needs using, inter alia, performic acid.